The present invention is concerned with providing a telephone service system at a location remote from both the subscribers to the system and the telephone central office.
In recent years numerous advanced services that can be provided to telephone subscribers have been developed. These advanced services have only been available, however, either directly through the telephone company (referred to herein as "TELCO") or to a limited extent by the installation of specialized complex equipment directly at the subscriber location. Due to both the high cost of directly renting such services from the telephone company and the high cost of a subscriber independently installing such specialized equipment, such services have been generally unavailable, or at least unaffordable, to most of the subscribers.
The lack of affordability of such sevices has been one reason for the development in recent years of what is referred to as a resale business in phone lines. The resellers have rented directly from the telephone company directdial long distance telephone lines, e.g. WATS lines, and then have resold access to such lines to various subscribers. In addition, some forms of limited services have been provided by telephone answering systems, e.g. the answering of calls and taking of messages, for various subscribers. The services made available by these types of systems, however, are extremely limited and do not afford the subscribers the full scope of services that exist but only can be acquired at relatively high rates directly from TELCO.
The telephone answering systems currently in existence have been coupled to the subscriber telephone lines either in a parallel connection between the subscriber lines and the telephone central office or by call forwarding of a call passing through the telephone central office. Exemplary of the various types of parallel connections that have been made of the telephone answering systems to the connection between the subscriber lines and the telephone central office are those embodiments described in the following U.S. Pat. Nos.: 2,685,614 to W. J. Curtin; 2,971,061 to R. V. Judy; 2,985,721 to E. H. Gatzert; 3,179,750 to W. M. Reilly; 3,445,603 to P. R. Robinson; 3,637,947 to C. Breen; and, 4,140,879 to S. D. Hefferman.
The patents to Curtin, Judy and Gatzert all disclose various embodiments of telephone answering systems. The patent to Reilly describes a telephone switching system having equipment at a private branch exchange (PBX) that minimizes the number of incoming calls requiring services of the local PBX operator. The patent to Robinson describes a circuit for tripping the ringing in an intercept circuit before an announcement is applied to the intercept telephone line. The patent to Breen describes a call forwarding arrangement that can be employed in telephone answering service systems. The patent to Hefferman describes a control circuit for transfer of auxiliary telephone equipment that utilizes the customers own tip and ring lines to allow the customer to selectively transfer incoming calls from a primary equipment location to an auxiliary equipment location such as an answering service.
In an attempt to modernize the older existing telephone central offices having electromechanical switching systems and not electronic switching systems (typically referred to as "ESS") so as to provide custom calling type services, certain equipment has been developed for incorporation directly in the telephone central offices. Exemplary of such equipment is the equipment offered by Summa Four, Inc. under the designation ACCESS 4075 . Such equipment is a plug-in system that can be put on line directly in the telephone central office with connections to the main frame between the subscriber line appearance and the office switching equipment. This type of equipment is provided to and utilized by the telephone central offices for enhancing the types of services they are capable of providing to their various subscribers. The system enables TELCO to then provide the following services: incoming call alert signalling; call forwarding; abbreviated dialing; conferencing; DTMF dialing; instant re-call; restrictive use control; ring-back signalling; and remote programming. All of these services are typically available in the more modernized ESS TELCO offices.
Certain other limited types of series connected equipment have been made available for incorporation directly at the subscriber premises. Such equipment has been provided for enhancing certain services and is incorporated into the subscriber system by way of plug-in jacks directly into the subscriber's circuit. While attempts may have been made for the provision of remote supplemental services coupled into the telephone system by way of a series interconnection, there is no known successful system that has been provided.
Moreover, the prior art fails to provide an efficient arrangement wherein a switching structure provides special services, including receptionist services, to a plurality of subscribers and requires a smaller number of additional lines than the number of subscribers.